‘Burning’ Giant Hogweed named as next big threat to properties

Like Japanese Knotweed and Himalayan Balsam, Giant Hogweed was brought to the UK as an horticultural oddity but has escaped and grows into dense colonies.

A flowering giant hogweed alongside a road.

Fears are growing that an invasive plant that looks like an enormous cow parsley that can wipe 15% off property prices is about to wreak havoc in Scotland.

Giant Hogweed (main picture) is a highly caustic plant that when it’s fully grown can reach towering heights of between 1.5 meters to 5 meters and forms a rosette of jagged, lobed leaves in the first year before sending up a flower spike in the second year and then setting seed.


But experts at Complete Weed Control are warning that the parlous plant could be on the march much earlier than expected after an early growth spurt due to mild wet weather.

Giant Hogweed spotted near Musselburgh, Scotland.
Giant Hogweed spotted near Musselburgh, Scotland.

They have already spotted young shoots of the rapidly-spreading and dangerous plant emerging from winter dormancy in March – unusually early for the enormous Heracleum Mantegazzianum whose sap can cause severe burns as well as scarring and chronic dermatitis.

March had 27% more rainfall than normal in the UK – and that it could lead to greater infestations of the plantthat can knock as much as 15% off house prices because of the utter chaos it can cause.


Keith Gallacher, Director at Complete Weed Control, says: “Our teams saw the much-earlier-than-expected appearance of the young Giant Hogweed during routine inspections in East Lothian, near Musselburgh.

Keith Gallacher, Complete Weed Control
Keith Gallacher, Complete Weed Control

“With such an early start, and with the rate of growth of which the plants are capable, it is likely that 2024 will be a bumper year for this rapacious invader.”

Like many invasive species, such as Japanese Knotweed and Himalayan Balsam, Giant Hogweed was brought to the UK as an horticultural oddity. But now it has escaped and, without any natural enemies, it grows into dense colonies, especially along watercourses.

Gallacher adds: “It is part of the Apiaceae family, which includes carrots, parsnip, cumin, coriander and parsley but its dense foliage prevents light reaching the soil underneath, killing off native plants and leading to rapid soil erosion.

“If you leave it too late, the plants get larger and become more difficult to spray, and require more herbicide. But if you do it too early and you get the torrential rains like we’ve had these last few weeks, the herbicide won’t have much effect.”

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